Arc-break device



June 13, 1961 J. BERNATT ARC-BREAK DEVICE 4 Sheets-Sheet 1 Filed June 2,1958 FlG.I

June 13, 1961 J. BERNATT 2,988,610

ARC-BREAK DEVICE Filed June 2, 1958 r 4 Sheets-Sheet 2 June 13, 1961 J.BERNATT ARC-BREAK DEVICE 4 Sheets-Sheet 4 Filed June 2, 1958 Ivor/mew:

2,988,610 ARC-BREAK DEVICE Joseph Bernatt, Guelph, Ontario, Canada,assignor to James R. Kearney Corporation of Canada Limited, Guelph,Ontario, Canada, a corporation of Canada Filed June 2, 1958, Ser. No.739,185 2 Claims. (Cl. 200-48) This invention concerns are break devicesand more particularly devices used in association with a high voltageswitch and designed to establish a temporary by-pass circuit around theswitch blades during the opening motion so as to allow the switch bladesto be separated from their contacts without drawing an arc. Thetemporary circuit established by the are break device is then rapidlybroken and the arc is drawn between two members of the by-pass circuitso as to avoid injury to the members of the main switching circuit.

The switching of long transmission lines presents many serious problems,one of these being the tendency of switching equipment to drawdestructive arcs due to surge currents. This tendency is more pronouncedthe longer the switched portion of line is. Various types of breakerdevices have been proposed in the past, but all of them have beenunsatisfactory because of their are drawing properties which imposeserious limitations on the length of line with which they can be used.Such devices previously proposed are predominantly of one of thefollowing types: In the usual form, the temporary by-pass circuit isestablished by a flexible rod in the form of a whip which is engaged bya hook on the contact structure and is bent by the opening of the switchblade until it finally snaps free of the hook. This type of arc breakerhas several disadvantages. For one, its thinness renders it ratherfragile, particularly under severe icing conditions. A seconddisadvantage is that by virtue of the very elasticity which produces itsbeneficial effects, the rod has a tendency to oscillate uncontrollablyafter release with a resultant detrimental effect on its mechanical andare breaking properties.

Another type of arc break device previously proposed is the type inwhich a spring loaded nonilexible member attached to the contactstructure rests on another nonfiexible member attached to the switchblade structure and rides thereon until the switch blade structure hasbeen raised to an angle where the contact rod becomes disengagedtherefrom. The contact rod is then swung back toward the contactstructure by its spring. This type of are breaker has provenunsatisfactory due to its tendency to strike the arc toward the contactstructure, and also because it requires a separate operation afterreclosing the switch to return the arc break device to its operativeposition.

A third type is so constructed that when the switch blade is opened, anauxiliary contact finger establishes the by-pass circuit. As the openingcontinues, the movement of the switch blade trips a latch, and a springwithdraws the auxiliary finger into an arc-extinguishing tube. Asidefrom its high cost, and aside from being subject to malfunctioning dueto icing, this type of switch makes difiicult a visual determinationwhether the auxiliary finger has been re-set, and it is thereforepotentially unsafe.

None of the prior art devices of which I am aware could be so designedas to allow the switch blade to be moved almost fully to theopen-circuit position, or even rotated more than 60 away from theclosed-circuit position before the arc breaker opens. In order to obtainmaximum protection against line surges, and consequently in order toallow the maximum line length between switches, it is essential that theswitch blade be at least 60 out of closed position before the arcbreaker opens.

My invention makes it possible to open the switch blade nite Statesatent C) to any desired angle, even beyond 135 if necessary, before thearc breaker opens.

I have found that the difiiculties inherent in the prior art structuresmentioned above can be eliminated and the effective switchable length ofline can be tripled by constructing the arc break device in the form ofa heavy spring loaded interrupting member mounted on the switch bladestructure and engaged by a hook on the contact structure, wherebypositive breaking action is assured and greater breaking speeds can beobtained.

It is therefore an object of our invention to provide an arc breakdevice which is sturdy, positive in its action, and uninfluenced byadverse weather conditions.

The mode of operation of my invention will be'readily apparent from thefollowing description taken in conjunction with the attached drawings,in which:

FIG. 1 is a perspective view of a disconnect switch carrying the arcbreak device of my invention, as it would appear mounted on a pole;

FIG, 2 is a side elevation of the same;

FIG. 3 is an end view of the structure shown in FIG. 2;

FIG. 4 is a like view showing the switch in the course of the openingmovement;

FIG. 5 is a top plan view of the device shown in FIG. 2;

FIG. 6 is a like view showing the switch in the fully closed position;

FIG. 7 is a section along line 77 of FIG. 5; and

FIG. 8 is a section along line 88 of FIG. 7.

In the preferred embodiment of my invention, the arc break device isused in conjunction with a disconnect switch of the type having a fixedbase, which is mounted on a pole, cross-arm, or other suitable mountingmeans. The base supports three insulators, one of which supports thecontact structure, and the other two of which support the switch bladeand its operating mechanism. The operating mechanism of the switch is sodesigned that, when the operating lever is rotated in a plane parallelto that of the base, an operating linkage first rotates the switch bladearound its axis, and then lifts it away from the contact. Upon closingof the switch, the operation is reversed, with the switch blade beingrotated around its axis after it has becomeseated in the contact. Thepurpose of this construction is to insure proper electrical contactbetween the switch blade and the contact member. In accordance with myinvention, I provide anvarc rod eccentrically mounted on the switchblade itself, and connected to the switch blade through the intermediaryof a mounting bell containing a spring which tends to rotate the arc rodin a counter-clockwise direction. The bell, besides constituting abearing for the arc rod, also protects the spring from the weather. Thecounter-clockwise movement of the are rod is limited by one or more stopmembers, also mounted on the switch blade, so as to prevent the arc rodfrom going beyond a position essentially parallel to the switch blade.Movement of the arc rod is further restricted by a hook member fixedlymounted on the contact structure. When the switch is opened, therotation of the switch blade first causes the arc rod to enter into firmelectrical contact with the hook structure. As the switch blade israised out of contact with the main contact member, the electricalcircuit is maintained through the arc rod and the hook structure.-As'the switch blade is raised further, the eccentricity of the axis ofthe arc rod mounting bell with respect to the axis of rotation of theswitch blade during its opening movement causes the arc rod to bewithdrawn from the hook. When the switch blade reaches a predeterminedposition (approximately from its closed position in our preferredembodiment), the end of the arc rod comes free of the hook, and israpidly moved away from the hook structure by its own powerful spring.The spring impels the arc rodto move into parallelism with-the switchblade, where the shock-absorbing stop members attached to the switchblade bring the arc rod to rest in the open position. When the switch isclosed, the stop members push the arc rod along with the switch blade,and into engagement with the hook structure releasing it only when theswitch reaches its fully closed position.

Referring now to the drawings, and particularly to FIG. I, a standarddisconnect switch, embodying the arc break device of my invention, isgenerally shown at 10. The switch is normally mounted in a verticalposition on a pair of cross-arms 12, which. in turn, are attached to apole 14. The position of the switch 10 is normally such that the blade16 moves upwardly and rearwardly when the switch is opened. The switchis operated by an operating lever 18, which protrudes from the side ofthe base, and can be engaged by any desired operating tool or mechanism.A clockwise pull on the operating lever 18 will open the switch 10.

In FIGS. 1 through 6, the base of the switch 10 is shown at 20. The base20 may be formed of any suitable material, such as channel iron. Threeinsulators, 22, 24, and 26, are mounted on the base 20. The insulators24 and 26 are fixed, whereas the insulator 22 is rotatably mounted, sothat it can be turned by the operating lever 18. A universal linkage,composed of three arms, 28, 30, and 32, connects the top end ofinsulator 22 to the switch blade 16 in such a manner that, wheninsulator 22 is turned, the blade 16 undergoes an axial rotary motion,followed by an opening motion around shaft 34. Shaft 34 is fixedlymounted with respect to insulator 24, and forms a part of terminalstructure 36. A conventional bridging braid assembly 35, 37 may be usedto provide a secure electrical contact between blade 16 and structure36.

The motion of blade 16 is accomplished in the following manner: At thestart of the rotation of insulator 22, and consequently of arm 28attached thereto, the force exerted on the linkage 28, 30, 32, is in adirection transverse to the length of the base. This results in a forceof similar direction at pivot point 38, which, in turn, results in anaxial rotation of blade 16, due to the eccentricity of the latter forcewith respect to the axis of the blade 16. The resultant twist in thelinkage is absorbed by arm 30, which has a tubular outer portion 40, anda concentric inner portion 42, rotatable with respect to each other. Inthe second phase of the motion of insulator 22, and consequently arm 28,the force exerted on pivot point 44 becomes increasingly longitudinalwith respect to the base 20. This results in rearward movement of thearm 30, and. due to the eccentricity of pivot point 38 with respect toshaft 34, in an opening motion of blade 16 around shaft 34.

The live terminal 46 of the switch 10 is fixedly mounted on insulator26, and is electrically connected to a jaw contact 48, which receivesthe end portion '50 of the blade 16 when the switch 10 is closed.Adjacent the contact 48, the terminal structure 46 also supports a pairof arcing horns 52 and 54. The horn 54 has formed on it a protuberance56, which projects into the path of the arc rod 58. The other born, 52,is of resilient construction, and serves to urge the arc rod 58 againstthe horn 54, so as to assure good electrical contact therewith. The arerod 58 is attached, at its lower end, to a rotary bell 60, journaled ona shaft 62 (FIG. 7), and biased for rotation by a spring 64. The shaft62 is attached to the blade 16 by bracket 66, and a strap 68 insuresgood electrical connection between the blade 16 and the arcing rod 58.

A stop member 70 is mounted near the upper end of blade 16, and, ifdesired (particularly in the larger size switches), a second stop member72 may be provided beyond the upper end of blade 16. The stop members.70 and 72 are rigidly connected together by a brace 74. ,Each of thestop members 70 and'iZ .is provided with a rubber or othershock-absorbing pad 76, against which the arc rod 58 comes to rest.

In operation, the switch 10 is opened in the manner describedhereinabove, by a clockwise pull on operating lever 18. As the blade 16is drawn out of contact with the jaw contact 48 in the latter portion ofthe motion of operating lever 18, the arc rod 58 is engaged byprotuberance 56, and is thereby held in electrical contact with theterminal structure 46, until the blade 16 has been moved through apredetermined are which in our preferred embodiment is at least 75 orDuring this motion of the blade 16, bell 60 rotates against the bias ofspring 64, while, at the same time, are rod 58 moves in a substantiallyrearward direction until its end 76 comes free of protuberance 56. Atthat moment, the arc rod 58 becomes free to move upward and rearward,and the force of spring 64 propels it very rapidly in a counterclockwisedirection around shaft 62, until arc rod 58 comes to rest against theshock-absorbing pads 76 of the stop members 70 and 72. Due to the suddenand rapid opening motion of arc rod 58, the resulting arc is quicklybroken, and any burning which may nevertheless occur is confined to thehorn 54 and the tip of the arc rod 58, where it can do no substantialdamage.

When the switch is reclosed by moving operating lever 18 forward, thestop members 70 and 72 carry are red 58 right along with blade 16 duringthe closing motion. Due to the elasticity of horn 52, are rod 58 can beforced through the gap 78 between protuberance 56 and horn 52, so thatare rod 58 is once again in operative position when switch blade 16becomes fully closed.

It will be seen that I have invented a simple, inexpensive, sturdy, safeand effective are breaking device for use with a switch of the typedescribed. It should, however, be kept in mind that my invention is inno way limited to use with a disconnect switch of the type shown. Infact, the arc break device of my invention could readily be used withother types of electrical equipment, in which its features can be put togood advantage. Also, my arc break device need not be mounted on theswitch blade, but may for example be eccentrically mounted on shaft 34.Many other modifications are possible within the spirit of my invention,and therefore, I do not desire to be limited by the embodiment describedherein, but only by the scope of the following claims.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent is:

1. In an electric switch having a fixed contact facing in one direction,a movable contact arm, and a hinged mounting for said contact arm onsaid switch, spaced from said fixed contact, and located adjacent oneend of said contact arm to provide for swinging movement of all portionsof said contact arm spaced from said hinge through curved paths towardand away from said fixed contact and for movement of the other end ofsaid contact arm into and out of engagement with said fixed contact, thecombination of, an are breaking device comprising a rigid bar in partcoextensive with said contact arm and having a tip to which the arc isconfined, a hinge connection and an electric connection between one endof said bar and said contact arm and located at a portion of saidcontact arm adjacent said hinged mounting therefor, which portion swingstoward and away from said fixed contact, said hinge connection mountingsaid bar for swinging movement in a plane parallel to the path ofswinging movement of said contact arm, stop means fixed to said movablecontact arm adjacent the other end of said contact arm and projectinglaterally into overlying relation to the path of swinging movement ofthe other end of said bar relative to said contact arm, spring meansconnected between said contact arm and said bar biasing said bar withrespect to said contact arm in a direction toward said overlying stopmeans, a hook means mounted on said switch facing in the oppositedirection to said fixed contact, adjacent thereto and electricallyconnected therewith, and adapted to overlie the other end of said rigidbar adjacent said arcing tip when said switch is closed, yielding meansadjacent said hook means and located to guide the other end of saidrigid bar around and into said hook means when said rigid bar ispropelled by said stop means in the direction of said hook means onmovement of said contact arm toward said fixed contact, said yieldingmeans being positioned beside said hook means to engage said n'gid barsimultaneously with said hook means to assure good electric contact witha portion of said bar adjacent said tip, and means to bias said yieldingmeans in a direction with respect to said hook means to preventdisengagement of said rigid bar from within said hook means on openingof said switch until movement of the portion of said contact armadjacent said hinge connection in a direction away from said fixedcontact has produced the other end of said rigid bar from within saidhook means.

2. The combination as defined in claim 1 in which a shock absorbing padis mounted on said contact arm adjacent said stop means, in a positionto absorb the recoil from impact of said bar, produced by the force ofsaid spring means thereon, during the movement of said bar by saidspring after the end of said bar slides from within said hook means.

References Cited in the file of this patent UNITED STATES PATENTS Re.22,853 Crabbs Mar. 18, 1947 2,308,026 Rawlins Jan. 12, 1943 2,750,'460Kast June 12, 1956

